1. Field of the Invention
This invention relates generally to a method and apparatus for the percutaneous introduction of a paddle style lead into the space near the spinal cord of a patient. More specifically, this invention relates to the introduction of a paddle style lead whereby the paddle style lead is stiffened during introduction and implantation and becomes flaccid once implanted. Moreover, this invention relates to the percutaneous introduction of the paddle style lead into the spinal column area through a needle with an oblong cross section.
2. Description of Related Art
Spinal cord stimulation is used to treat a multitude of disorders including multiple sclerosis, spinal cord injury, cerebral palsy, amyotrophic lateral sclerosis, dystonia, torticollis and other neurological disorders. Spinal cord stimulation is also useful for treating pain including intractable malignant and nonmalignant pain. Neural stimulation electrodes and leads implanted in the epidural space of the spinal cord of a patient stimulate selected locations of the spinal cord for treatment of pain and various conditions.
Surgically implantable paddle style leads, or flat leads, and percutaneous insertable wire leads for the spinal cord have been in use for some time. These paddle style, or flat leads, and wire leads are used for electrical stimulation of neurons in the spinal cord. Two types of leads are generally used for spinal cord stimulation: 1) wire and 2) paddle.
Typically, a wire lead is introduced into the spinal column using a needle and a stylet assembly. The needle and stylet are inserted into the spinal column area between adjacent vertebrae until the tip of the needle and stylet are advanced into the epidural space of the spinal column area. The stylet is withdrawn and a wire lead is inserted through the open area or lumen of the needle and into the epidural space to a selected location adjacent to the spinal cord. Some needle and stylet assemblies have a curved distal tip to facilitate introduction of the lead at an angle to the axis of the lumen portion of the needle. The needle typically has a side opening or orifice at its distal end for insertion of the lead into the selected location of the spinal cord. In some assemblies, the stylet may fill the entire lumen cavity including the side opening of the needle to prevent the collection of tissue in the lumen cavity during insertion of the needle. The stylet can also provide rigidity to the needle body for use during insertion.
Current needle technology requires that all leads be of a circular cross section in order to be placed through the lumen portion of the needle into the epidural space. Needles used for insertion of the wire leads typically have a circular cross section between 14 and 18 gauge.
The paddle style or flat leads are generally rectangular shaped flat paddles that must be surgically implanted. To introduce a paddle style lead into the epidural space percutaneously using needle insertion, the paddle lead must be rolled to a circular shape to slide through the typical circular cross section needle. The method of rolling the paddle lead and inserting through a needle and unrolling the paddle style lead has not been perfected for use. The only way to insert a paddle style lead is by a surgical procedure known as a laminotomy, a laminectomy, or similar surgical procedure. Because the paddle style lead must be surgically implanted, anesthesiologists may not perform the procedure.
Accordingly, there remains a need in the art for a non-surgical method of inserting a paddle style or flat lead into the spinal cord area.